Automotive vehicles typically utilize a lead-acid battery to start the vehicle and to operate accessory loads when the engine is not running. These batteries are generally of a square or rectangular shape and are usually located in the engine compartment in the proximity of the starter and alternator, which are attached to the engine.
Over the course of normal operation, dirt and water reaching the engine compartment can collect on the battery case and can provide a conductive medium for electrical current to leak between the terminals, thereby draining electrical charge from the battery. For this reason, it is recommended to routinely inspect and clean the battery terminals. However, due to the limited packaging space in the engine compartment, it can often be difficult to access the terminals in order to provide the desired maintenance or to remove and replace the battery.
In addition to the limited packaging space in the engine compartment, high temperature and vibration from the engine can degrade the performance of the battery and shorten battery life. This results in a greater need for regular inspection, maintenance and replacement.
Locating the battery in the engine compartment also creates a challenge when designing the vehicle for crashworthiness. A battery is generally a rigid structure that maintains its shape during a crash. This physical property creates a challenge for vehicle designers in that the battery consumes space that may otherwise be used to provide a crush zone in the vehicle structure.